"We take the view that the biggest indicator to have an impact on the fund is the fees. So we put a lot of focus on fees."

Groth said Canstar's ratings did not take investment performance into account because a substantial review of academic research concluded there was no strong evidence that one fund could perform better than any other over the long term.

Groth, who is based in Brisbane, said fees were considered to be so important in Australia that superannuation schemes had to include a statement saying that fees can have a significant impact on the end balance.

"Over the long term what you pay will have an impact on your retirement savings' balance and should be taken into account. Whether it is a big fund or a small one make sure you are getting value for money and that you are comfortable with that."

Most KiwiSaver schemes charge a flat membership fee on an annual basis as well as having operating costs which have to be paid for out of a fund's assets.